Epstein et al, commonly assigned co-pending U.S. utility patent application Ser. No. 578,180, filed Feb. 8, 1984, now abandoned, incorporated herein by reference, discloses an INFUSION SYSTEM HAVING PLURAL FLUID INPUT PORTS AND AT LEAST ONE FLUID OUTPUT PORT having a processor-controlled cam assembly for selectively controlling a plurality of input fluid valves and a patient output valve, among others. A processor is operative under program control to selectively actuate the plural fluid input port valves and the output patient valve in a selectable time sequence to administer infusates into the circulatory system of a patient undergoing infusion therapy. The plurality of fluid input port valves and the patient output port valve are integrally formed in a disposable fluid cassette, and the fluid cassette is itself further described and claimed in its ornamental design features in commonly owned co-pending U.S. design patent application Ser. No. 578,175, filed Feb. 8, 1984, now abandoned, incorporated herein by reference.
The processor controlled cam assembly includes a first singly-lobed cam mounted for rotation with the shaft of a processor-controlled stepper motor. A plurality of pivotable input valve rocker arms having rollers are spaced about the first cam with the rollers circumferentially disposed around the cam surface. A second doubly-lobed cam is mounted for rotation with the shaft of the stepping motor subjacent the first cam, and a pivotable patient output valve rocker arm is spaced with its roller adjacent the second cam. A plurality of plungers individually associated with an input or an output valve are mounted to corresponding rocker arms, and compression springs are mounted to respective plungers that are operative to so urge the plungers as to maintain the plural valves in a normally closed condition. The processor is operative to controllably rotate the stepper motor to bring the lobe of the first cam into abutting relation with a selected roller for actuating via its plunger the corresponding fluid input valve and is operative to bring either of the lobes of the second cam into abutting relation with its roller for actuating via its plunger the patient output valve.
The lobes of the several cams are so phased that it is not possible for an input valve to be simultaneously actuated with the patient output valve to prevent, among other things, accidental gravity flow infusion. A processor controlled solenoid having a ram in abutting relation with the output valve rocker arm is provided for actuating the patient output valve at the same time with an input valve such as during system priming, among others.